Added histogram to track distribution of requested idle notifications.

src/heap.cc

Index: src/heap.cc
diff --git a/src/heap.cc b/src/heap.cc
index c53c9a75ec71ee5ae6ce36e8588c9e1a2b2c5dc4..91fdce8dcb2ab74f8d5f5ede2294ff8d53779ebe 100644
--- a/src/heap.cc
+++ b/src/heap.cc
@@ -53,17 +53,18 @@ Heap::Heap()
       amount_of_external_allocated_memory_at_last_global_gc_(0),
       isolate_(NULL),
       code_range_size_(0),
-// semispace_size_ should be a power of 2 and old_generation_size_ should be
-// a multiple of Page::kPageSize.
+      // semispace_size_ should be a power of 2 and old_generation_size_ should
+      // be
+      // a multiple of Page::kPageSize.

[rmcilroy, 2014/07/25 09:38:29]

move up to line above

       reserved_semispace_size_(8 * (kPointerSize / 4) * MB),
-      max_semi_space_size_(8 * (kPointerSize / 4)  * MB),
+      max_semi_space_size_(8 * (kPointerSize / 4) * MB),
       initial_semispace_size_(Page::kPageSize),
       max_old_generation_size_(700ul * (kPointerSize / 4) * MB),
       max_executable_size_(256ul * (kPointerSize / 4) * MB),
-// Variables set based on semispace_size_ and old_generation_size_ in
-// ConfigureHeap.
-// Will be 4 * reserved_semispace_size_ to ensure that young
-// generation can be aligned to its size.
+      // Variables set based on semispace_size_ and old_generation_size_ in
+      // ConfigureHeap.
+      // Will be 4 * reserved_semispace_size_ to ensure that young
+      // generation can be aligned to its size.
       maximum_committed_(0),
       survived_since_last_expansion_(0),
       sweep_generation_(0),
@@ -130,6 +131,7 @@ Heap::Heap()
       full_codegen_bytes_generated_(0),
       crankshaft_codegen_bytes_generated_(0),
       gcs_since_last_deopt_(0),
+      idle_notification_histogram_(NULL),
 #ifdef VERIFY_HEAP
       no_weak_object_verification_scope_depth_(0),
 #endif
@@ -4268,6 +4270,8 @@ bool Heap::IdleNotification(int hint) {
   intptr_t step_size =
       size_factor * IncrementalMarking::kAllocatedThreshold;
 
+  isolate()->stats_table()->AddHistogramSample(idle_notification_histogram_,
+                                               hint);
   HistogramTimerScope idle_notification_scope(
       isolate_->counters()->gc_idle_notification());
 
@@ -5132,6 +5136,10 @@ bool Heap::SetUp() {
     if (!ConfigureHeapDefault()) return false;
   }
 
+  idle_notification_histogram_ = isolate()->stats_table()->CreateHistogram(
+      "V8.IdleNotification", 0, kMaxIdleNotificationHistogramSample,

[rmcilroy, 2014/07/25 09:38:29]

ditto (V8.IdleNotificationHint or V8.IdleGCAllottedTime).

+      kMaxIdleNotificationHistogramSample + 1);
+
   base::CallOnce(&initialize_gc_once, &InitializeGCOnce);
 
   MarkMapPointersAsEncoded(false);